\begin{tabular}{r@{ $\pm$ }lr@{ $\pm$ }l}
\multicolumn{2}{c}{$R [\unit[]{\ohm}]$} &\multicolumn{2}{c}{potenziometro} \\ 
\hline
9.84 & 0.12 & 0.98 & 0.01 \\ 
21.86 & 0.12 & 2.27 & 0.01 \\ 
32.98 & 0.12 & 3.26 & 0.01 \\ 
38.59 & 0.12 & 3.81 & 0.01 \\ 
55.85 & 0.13 & 5.52 & 0.01 \\ 
67.35 & 0.14 & 6.66 & 0.01 \\ 
79.64 & 0.15 & 7.89 & 0.01 \\ 
\end{tabular}
